attajaj: attaja-,
Adj.: proceeding from oneself, born from oneself. It is a compound of:atta-, N.m.: it is the compound
form of the word attan-, N.m.: see above.-ja-, Adj.suf.: born, proceeding.
It is derived from the verb root jan- (to give birth, to produce).Nom.Sg.n. = attajaj.

attasambhavaj: attasambhava-,
Adj.: originating from oneself. It is a compound of:atta-, N.m.: it is the compound
form of the word attan-, N.m.: see above.sambhava-, N.m.: origin, production.
It is derived from the verb root bhu-
(to be) with the prefix sam- (together).Nom.Sg.n. = attasambhavaj.

This verse consists of two syntactically
separate sentences. They are: 1) attana
hi kataj papaj
attajaj attasambhavaj
(the evil is done by oneself, proceeding from oneself, originating from
oneself). The subject is the noun papaj
(evil, nominative singular). It has three attributes, the adjectives attajaj
(proceeding from oneself, nominative singular) and attasambhavaj
(originating from oneself, nominative singular). The third attribute is
the past participle kataj (done, nominative
singular) with the noun attana (by
oneself, instrumental singular) as an attribute. The particle hi
(indeed) serves mainly form metrical purposes. The verb is omitted, implying
the verb "to be". 2) abhimatthati dummedhaj
vajiraj v'asmamayaj
manij ([it]
crushes the fool, just like a diamond [crushes] a hard gem). The subject
is omitted; the word papaj
(evil) from the previous sentence is implied. The verb is abhimatthati
(crushes, 3rd person, singular, active, indicative, present
tense). The object is the adjective dummedhaj
(foolish one, accusative singular). There is a clause in this sentence,
vajiraj v'asmamayaj
manij (just
like a diamond [crushes] a hard gem). Here, the subject is the noun vajiraj
(diamond, nominative singular). The verb is omitted; implying the verb
abhimatthati from the main sentence. The object is the noun manij
(gem, accusative singular) with its attribute, the adjective compound asmamayaj
("stone-made", hard; accusative singular). The particle va (like,
as) connects the clause to the main sentence.

Commentary:

There was a lay disciple named Mahakala.
Once he spent the night in the monastery, observing the eight precepts
and meditating. In the morning, on his way home, he stopped by a pond to
wash his face. On the same night some thieves broke into a house and were
chased by the owners. The thieves dropped their stolen things in front
of Mahakala and
ran away. The owners mistook Mahakala
for a thief and beat him up. Mahakala
died of his injuries. Some monks discovered his body and reported the matter
to the Buddha. The Buddha explained, that in one
of his previous lives, Mahakala
fell in love with a certain woman and had beaten her husband to death.
He then added this verse, saying that one's own evil deeds surely come
back to their doer and fall back on his head.